1. Field of the Invention
The present invention relates to a system for separating and recovering waste fluid and a spin coater.
The application is a counterpart application of Japanese Application Serial Number 044540/2001, filed Feb. 21, 2001, the subject matter of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, in photolithographic processing, which is a part of a process by which a semiconductor IC is fabricated, photoresist is coated on a substrate using a photoresist coating apparatus that is generally called a spin coater. In this case, a large amount of waste fluid is generated during a step in which the photoresist is coated on the substrate and a step in which excess photoresist is washed and removed from the substrate with a rinse. Therefore, it is desirable to separate and recover the photoresist liquid and the like from the waste fluid to reuse.
As a method for separating and recovering various waste fluids generated during photoresist coating in the photoresist coating apparatus described above, there have been provided systems such as, for example, the following. Namely, a plurality of cups is disposed in a vertical direction and a mechanism is disposed for moving the substrate in the vertical direction. The substrate is moved by the mechanism and stopped at positions corresponding to the respective waste fluid separating cups. Coating of the photoresist on the substrate and subsequent rinsing of the substrate are separately carried out at respectively different positions, whereby the photoresist waste fluid and rinse waste fluid are separated.
The respective photoresist waste fluid and rinse waste fluid that have been separated into the respective waste fluid separating cups as described above are passed through separate waste fluid hoses for separately recovering the waste fluids, to then be stored in separate waste fluid tanks.
The photoresist is basically composed of a resin component and a solvent for diluting. Since the solvent in the photoresist waste fluid recovered by the above-described method has volatilized, the viscosity of the photoresist waste fluid is higher than that of the photoresist before use. By again adding solvent to the waste fluid having a high viscosity in order to restore it to its initial viscosity, the photoresist waste fluid can be reused without being discarded. This operation is called xe2x80x9cphotoresist reclamationxe2x80x9d.
However, in the conventional photoresist coating apparatus, there are limitations on the method of exhaust in the waste fluid separating cups due to problems relating to the way the waste fluid separating cups are structured. Since it has not been possible to sufficiently carry out exhaust, minute, gaseous particles of the waste fluids floating in the cups are not discharged together with the exhaust. A large amount of the particles thus adheres to a back surface of the substrate, whereby product quality deteriorates.
By separating the photoresist waste fluid and the rinse waste fluid, the photoresist waste fluid in the waste fluid separating cup tends to dry, and the resin in the photoresist waste fluid tends to solidify due to evaporation of the solvent in the photoresist waste fluid. This promotes build-up of the photoresist waste fluid in the waste fluid separating cup, and further, drying of the photoresist waste fluid in the waste fluid tank causes a loss in an amount thereof. Therefore, rate of recovery of the photoresist waste fluid is lowered.
Consequently, rate of reclamation of the photoresist is lowered due to a drop in the rate of recovery, and the amount of the solvent to be added is increased, whereby costs for reclaiming the photoresist increase.
Objects of the present invention are to provide a system for separating and recovering waste fluid and a spin coater, which solve problems in the conventional photoresist coating apparatus described above, which can completely recover photoresist waste fluid, which do not cause lower rate of recovery of the photoresist waste fluid due to drying of the photoresist waste fluid, and thus enable highly efficient photoresist separation and recovery.
To this end, the present invention provides a system for waste fluid separation and recovery when coating with a photoresist on a substrate using a fluid, the system comprising: a first cup in which the substrate is disposed when the substrate is being coated with the photoresist; a photoresist waste fluid groove connected by a path of fluid communication with the first cup; and an exhaust airflow generator for generating an exhaust airflow, which guides photoresist waste fluid from the substrate toward the photoresist waste fluid groove.
In this case, no gaseous particles remain floating in the vicinity of a photoresist coating position, and the gaseous particles can be prevented from floating toward and adhering onto a back surface of the substrate.
Further, the present invention provides a spin coater for coating with a photoresist on a substrate using photoresist and rinse liquid, the spin coater comprising: a chuck adapted for detachably mounting a substrate thereto, the chuck being movable between a first position for applying the photoresist to the substrate when mounted thereto, and a second position for applying the rinse liquid to the substrate; nozzles disposed for applying the photoresist and rinse liquid to the substrate mounted on the chuck; first and second cups extending around the chuck, wherein the first and second cups include walls of a height different from one cup to the other, wherein first cup captures photoresist waste fluid form the substrate when spun at the first position, and second cup captures rinse waste fluid form the substrate when spun at the second position; a photoresist waste fluid groove connected by a path of fluid communication with the first cup;
a rinse waste fluid groove connected by a path of fluid communication to the second cup; and
an exhaust airflow generator which generates an exhaust airflow that guides the photoresist waste fluid from the substrate toward the photoresist waste fluid groove.